What
prompts normal cells to transform themselves into cancerous
cells? Researchers from Texas institutions, including the
UT Health Science Center San Antonio, have identified factors
in the very first step of the process and reconstituted
this first step in the test tube. The latter accomplishment
was reported Sunday [Nov. 21] in the top-tier journal Nature
Structural & Molecular Biology.

SAN ANTONIO
(Nov. 22, 2010) —
The DNA molecule — the elegant, twin-stranded necklace of
life in all cells — gets broken and repaired all the time.
Breaks are caused by the body’s metabolic activities such
as energy consumption and environmental factors such as exposure
to ultraviolet light. Cancer results when the repair response
is absent or deficient.

“DNA breaks are considered to be a major instigator of cancer
cell development,” said Sang Eun Lee, Ph.D., associate professor
of molecular medicine at the UT Health Science Center San
Antonio. “When a break is detected, signals are sent to cells
that repair is needed.”

The early initiating step of the break repair and signaling
“has been quite elusive for some time because the factors
were not known,” Dr. Lee said. He was lead author of a paper
published recently in EMBO Journal that identified action
of a set of enzymes called Mre11 and Exo1.

In the Nature paper the researchers, who included the lab
of Tanya Paull, Ph.D., at UT Austin, “repeated the process
in a test tube because we now knew about Mre11 and Exo1,”
Dr. Lee said.

Dr. Lee’s research is supported by the National Institutes
of Health and he is a research scholar of the Leukemia &
Lymphoma Society. Collaborating from his laboratory are Eun
Yong Shim, Ph.D., assistant professor, and Kihoon Lee, a graduate
student.

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The University of Texas Health Science Center at San Antonio,
one of the country’s leading health sciences universities,
ranks in the top 3 percent of all institutions worldwide
receiving National Institutes of Health (NIH) funding. Research
and other sponsored program activity totaled a record $259
million in fiscal year 2009. The university’s schools of
medicine, nursing, dentistry, health professions and graduate
biomedical sciences have produced approximately 26,000 graduates.
The $739 million operating budget supports eight campuses
in San Antonio, Laredo, Harlingen and Edinburg.